Mr Erdogan today branded the hundreds of thousands who have taken to the streets in cities across the country as an "extremist fringe," and "a bunch of looters".

The protests began as a local demonstration against redevelopment on Gezi Park in Istanbul but that have escalated to a public outcry against what is perceived to be Mr Erdogan's increasingly authoritarian rule.

"There are those attending these events organised by extremists. This is not about Gezi Park anymore. These are organised events with affiliations both within Turkey and abroad," he told reporters at a press conference.

"If there are different opinions, different situations, different points of view and dissent, there is nothing more natural that being able to voice those differences," he was quoted as saying by the Anatolia news agency.

The two men are expected to compete against each other next year in Turkey's presidential election.

Mr Erdogan has been seeking to push through controversial constitutional reforms to increase the power of the presidency, which - after winning three landslide elections - he had seemed well placed to win.

His comments today, and the heavy response of the Turkish security forces against the largely peaceful protests, may have damaged his chances, however.

The demonstrations continued today in cities across Turkey. The most intense clashes in Istanbul took place in the early hours of the morning when protesters tried to storm Mr Erdogan's office, only to be repelled by police with teargas.

Turkey's main stock exchange dropped 6.4 percent upon opening today as investors worried about the destabilizing effect of the demonstrations on the economy.

"It's the stock market, it goes down and it goes up," Mr Erdogan said, playing down the significance of the drop. "It can't always be stable."

His suggestion that the demonstrations might have been arranged by foreign elements is resonant of the accusations made by ousted Libyan dictator Colonel Muammer Gaddafi, and embattled President Bashar al-Assad in Syria, who both sought to blame the opposition they faced on foreign interference.

Appearing defensive and angry, Mr Erdogan rejected comparisons with the Arab Spring uprisings: "We already have a spring in Turkey," he said, alluding to the nation's free elections. "But there are those who want to turn this spring into winter."